<script type="text/javascript">
		
	   function cambia(select,oCntrl){  
	      if (oCntrl.value == select.value){
	    	  oCntrl.value = -1;
	      }
	    } 
	    
	   function validar(form){
		   
		   if ((form.sel11.value == "-1") || (form.sel12.value == "-1") || (form.sel13.value == "-1") || (form.sel14.value == "-1")
				   || (form.sel21.value == "-1")|| (form.sel22.value == "-1")|| (form.sel23.value == "-1")|| (form.sel24.value == "-1")
				   || (form.sel31.value == "-1")|| (form.sel32.value == "-1")|| (form.sel33.value == "-1")|| (form.sel34.value == "-1")
				   || (form.sel41.value == "-1")|| (form.sel42.value == "-1")|| (form.sel43.value == "-1")|| (form.sel44.value == "-1")
				   || (form.sel51.value == "-1")|| (form.sel52.value == "-1")|| (form.sel53.value == "-1")|| (form.sel54.value == "-1")
				   || (form.sel61.value == "-1")|| (form.sel62.value == "-1")|| (form.sel63.value == "-1")|| (form.sel64.value == "-1")
				   || (form.sel71.value == "-1")|| (form.sel72.value == "-1")|| (form.sel73.value == "-1")|| (form.sel74.value == "-1")
				   || (form.sel81.value == "-1")|| (form.sel82.value == "-1")|| (form.sel83.value == "-1")|| (form.sel84.value == "-1")
				   || (form.sel91.value == "-1")|| (form.sel92.value == "-1")|| (form.sel93.value == "-1")|| (form.sel94.value == "-1")
				   || (form.sel101.value == "-1")|| (form.sel102.value == "-1")|| (form.sel103.value == "-1")|| (form.sel104.value == "-1")
				   || (form.sel111.value == "-1")|| (form.sel112.value == "-1")|| (form.sel113.value == "-1")|| (form.sel114.value == "-1")
				   || (form.sel121.value == "-1")|| (form.sel122value == "-1")|| (form.sel123.value == "-1")|| (form.sel124.value == "-1")
				   || (form.sel131.value == "-1")|| (form.sel132.value == "-1")|| (form.sel133.value == "-1")|| (form.sel134.value == "-1")
				   || (form.sel141.value == "-1")|| (form.sel142.value == "-1")|| (form.sel143.value == "-1")|| (form.sel144.value == "-1")
				   || (form.sel151.value == "-1")|| (form.sel152.value == "-1")|| (form.sel153.value == "-1")|| (form.sel154.value == "-1")
				   || (form.sel161.value == "-1")|| (form.sel162.value == "-1")|| (form.sel163.value == "-1")|| (form.sel164.value == "-1")){
			   alert("No has contestado a alguna pregunta");
			   return false;
		   }
		   else return true;
		   
	   }
<!--

//-->
</script> 